Ok.

they say we can't, but I'm not sure.. i mean, polyamory relationship exist too right? though I'm against it. well, maybe the second person that you love? cause if you truly loved the first one you wouldn't find the second attractive

It might be possible, because the capacity to love more than one person is a complex aspect of human emotions. However, you'll feel differently when you talk to them, tho.

The last one

In certain cases, it is possible to feel that way. But I personally believe that the amount or level won't be the same between one another. So, when we fell in love with two people at the same time, always choose the second one because what kind of love do you have until you let yourself fall for the second time with different person?

I personally think it is possible. But I think it'll be kinda different, I mean about our feelings towards them. Both may attract our attention, making us fall in love at the same time. But sometimes we feel something more about one of them, sometimes we feel more comfortable with one or the other. Choose someone who makes you feel at ease, feel safe, loved the most, the person you are most looking forward to receiving a message from. And if they're distant or you're rejected, they can make you feel really messed up.. maybe that's the person you really love.